PSI - Issue 44

Marco Gallo et al. / Procedia Structural Integrity 44 (2023) 618–625 Marco Gallo et al. / Structural Integrity Procedia 00 (2022) 000–000

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evaluated by looking at the demand to capacity ratio D/C value. Moreover, the soil properties have also been modified as three different categories were considered: B, C and D. The effect can be underlined in terms of vibration periods or in terms of bending moment and the effect on demand to capacity ratio D/C by considering the behavior factor q=3.0 previously evaluated. The following Figure 7 shows the percentage of reduction of the bending moment for each soil category and piers height, either for the fixed base and SSI base modelling.

0 20 40 60

h=3,0 h=4,5 h=6,0

%

Soil B

Soil C

Soil D

Fig. 7. Reduction percentage of the stressing bending moment varying soil type and piers slenderness.

7. Effect of SSI on retrofitting interventions Finally, the seismic retrofitting interventions have been provided. The piers can be retrofitted by adding a RC jacket with a new cover of concrete and reinforcing steel bars, useful both for bending moment and shear verification. The effects of the interventions are presented varying the thickness of the new concrete cover (s) and the diameter of the rebars ( f ).

Fig. 8. Reinforcing scheme.

Table 7. Interventions needed to retrofit and D/C resulting for each one.

Transversal direction - Fixed base - Soil B - q = 1,5 Transversal direction - Fixed base - Soil B - q = 3,0

f 16

f 18

f 20

f 22

f 24

f 16

f 18

f 20

f 22

f 24

s = 5cm 1,44

1,34

1,24

1,15

1,06

s = 5cm 0,72

0,67

0,62

0,57

0,53

s = 7,5cm 1,36

1,27

1,18

1,09

1,01

s = 7,5cm 0,68

0,63

0,59

0,55

0,51

s = 10cm 1,30

1,20

1,11

1,03

0,96

s = 10cm 0,65

0,60

0,56

0,52

0,48

s = 12,5cm 1,20

1,12

1,05

0,97

0,91

s = 12,5cm 0,60

0,56

0,52

0,49

0,45

s = 15cm 1,14

1,06

0,99

0,92

0,86

s = 15cm 0,57

0,53

0,49

0,46

0,43

Transversal direction - SSI - Soil B - q = 1,5

Transversal direction - SSI - Soil B - q = 3,0

f 16

f 18

f 20

f 22

f 24

f 16

f 18

f 20

f 22

f 24

s = 5cm 1,08

1,01

0,94

0,87

0,81

s = 5cm 0,54

0,51

0,47

0,44

0,41

s = 7,5cm 1,02

0,96

0,89

0,83

0,77

s = 7,5cm 0,51

0,48

0,45

0,42

0,39

s = 10cm 0,98

0,90

0,84

0,79

0,73

s = 10cm 0,49

0,45

0,42

0,39

0,37

s = 12,5cm 0,91

0,85

0,79

0,74

0,69

s = 12,5cm 0,45

0,42

0,40

0,37

0,35

s = 15cm 0,86

0,81

0,75

0,70

0,66

s = 15cm 0,43

0,40

0,37

0,35

0,33